When drilling single or multi-layer stacks, a favored method of stabilizing the drill spindle and workpiece is to press an independently actuated device extending forward of a drill spindle, known as a nosepiece or pressure foot, onto the workpiece surface. Applying this clamping force to multi-layers stacks reduces or eliminates interlaminar burrs from the drilling operation, and prevents drill chips from getting between the layers of materials, which could lead to the holes not lining up after the debris is removed.
Typically, the nosepiece extends beyond the drill tool when the drill tool is retracted. During the actual hole drilling operation, an independent spindle quill with a rotating tool is translated beyond the nosepiece plane.
For hand drilling and some machine drilling applications, a great number of clamping devices, such as Clecos, may be used to apply a squeeze to the stack every few inches. Alternately, external devices such as linear actuators or pneumatic cylinders may be used to apply force to the spindle nosepiece. The external devices are mounted on pairs on opposite sides of the spindle to apply balanced forces, or heavy structures are required to use a single offset device.
These external actuators add significant bulk to the spindle and reduce workpiece accessibility. The actuators and support structures also add weight to the drill spindle. Thus, although desirable results have been achieved using clamping mechanisms in accordance with the prior art, novel systems that are lighter and less bulky would have greater utility.